Pneumatic spring system

ABSTRACT

The invention relates to a pneumatic spring system which comprises a pneumatic spring cap and pneumatic cushioning bellows, a pneumatic spring piston with a lateral rolling surface and a base surface that is designed such that a multi-chamber system protrudes into the interior of the pneumatic spring piston. The aim of the invention is to provide a pneumatic spring piston that can be subjected to eccentric loads at a reduced weight and without a holding plate. The multi-chamber system and the fastening system are mounted in such a position that there is maximally one mirror plane perpendicular to the base surface of the pneumatic spring piston, in relation to the piston center axis, and that an eccentric rest surface of the pneumatic spring piston directly contacts the spring carrier.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicants claim priority under 35 U.S.C. §119 of German Application No.199 31 198.6 filed Jul. 7, 1999. Applicants also claim priority under 35U.S.C. §120 of PCT/DE00/02035 filed Jun. 23, 2000. The internationalapplication under PCT article 21(2) was not published in English.

DESCRIPTION

The invention relates to a pneumatic spring system comprising at leastthe following structural components, specifically

a pneumatic spring cover and a pneumatic spring bellows;

a pneumatic spring piston which in particular is made of plastic oraluminum, and which comprises a face area that is arranged opposite thepneumatic spring cover; a lateral roll-off surface for the pneumaticspring bellows to roll off on, and a base area that is designed in sucha way that a multi-chamber system projects into the interior of thepneumatic spring piston;

a first fastening system, which is arranged within the base area of thepneumatic spring piston; as well as

a reinforcement, in particular a longitudinal guiding rod or elementwith which the base of the pneumatic spring piston is anchored by themeans of the first fastening system as well as an additional secondfastening system.

A pneumatic spring system of said type is described, for example inpublished patent document EP 0 501 043 B1 (FIG. 2).

The pneumatic spring piston, which is referred to also as the roll-offpiston or immersion piston, is made of steel, plastic or aluminum,whereby the two last-mentioned materials are increasingly findingpreferred use because of their lower weight as compared to steel.Furthermore, the multi-chamber system of the pneumatic spring pistoncomprises a ring chamber in most cases, which extends within the edgezone of the base area, forming an annular outer edge and an inner edge;and one or a plurality of core chambers defined by bridges, such corechamber or chambers being arranged within the inner edge of the ringchamber. In addition, the pneumatic spring piston has the largestdiameter in most cases within the zone of its base area, so that awidening is formed in this way.

The pneumatic spring pistons known heretofore are constructed in such away that they have a plurality of mirror planes in conjunction with acentral support body. Pneumatic spring pistons that arerotation-symmetrical in relation to the center axis of the piston areknown as well.

Now, two variations exist with respect to the stress acting on thepneumatic spring piston:

The pneumatic spring piston is stressed centrically.

The pneumatic spring piston is stressed eccentrically, which is the casein particular in conjunction with a longitudinal guiding rod serving asthe spring support. This could be accomplished until now in conjunctionwith the piston construction described above only with the help of aholding plate made of steel, which is secured on the base of thepneumatic spring piston especially when a pneumatic spring piston madeof plastic is used.

Now, the problem of the invention is to provide a pneumatic springsystem of the type specified above, in conjunction with which thepneumatic spring piston can be stressed eccentrically while omitting aholding plate and achieving at the same time a reduction of the weight.

Said problem is solved according to the characterizing part of claim 1in that

the multi-chamber system and the first fastening system are arranged ina way such that only one mirror plane at the most is present verticallyin relation to the base of the pneumatic spring piston, namely withrespect to the center axis of the piston, with formation of an eccentricsupport surface for the pneumatic spring piston with direct contact withthe spring support.

Advantageous design variations of the pneumatic spring system as definedby the invention are specified in claims 2 to 27.

Now, the invention is explained in the following with the help ofexemplified embodiments and by reference to five drawings, in which:

FIGS. 1, 2 show two particularly advantageous construction variations ofthe multi-chamber system.

FIG. 3 shows a pneumatic spring piston made of plastic, with a metalinsert cooperating with a spring support;

FIGS. 4, 5 show two different views of a metal insert consisting of athreaded component and a reinforcing rib.

The following list of reference numerals and symbols applies inconjunction with said figures:

1,1′,1″ Pneumatic spring piston

2,2′,2″ Base area of the pneumatic spring piston

3,3′,3″ Face area of the pneumatic spring piston

4,4′,4″ Roll-off surface of the pneumatic spring piston

5,5′,5″ Ring chamber

6,6′,6″ Outer edge of ring chamber

7,7′,7″ Inner edge of ring chamber

8,8′,8″ Core chambers

9,9′ Main bridge

10,10′ Fastening bridge

11,11′,11″ First fastening system

12 Outer bridge (perpendicular to main bridge)

13 Inner bridge (perpendicular to main bridge)

14 Transverse bridge (parallel with main bridge)

15 Outer bridge (inclined relative to main bridge)

16 Inner bridge (inclined relative to main bridge)

17 Head chamber

18 Bridge (with curved shape

19 Spring arm (longitudinal guiding element)

20 Support surface

21 Bore drilled in spring arm

22 Longitudinal outer edge of spring arm

23 Threaded part of metal insert

24 Reinforcing rib of metal insert

25 Bores within the reinforcing rib

A, B, C, D Ring chamber segments H Overall height of pneumatic springpiston S Center axis of piston X Mirror plane

FIG. 1 shows a pneumatic spring piston 1 with the base 2, the face 3,the latter being arranged opposite the pneumatic spring cover, as wellas with the lateral roll-off surface 4, on which the pneumatic springbellows can roll off. Within the zone of its base area 2, the pneumaticspring piston has its largest diameter, with formation of a widening.Furthermore, the base area 2 is designed in such a way that amulti-chamber system projects into the interior of the pneumatic springpiston.

The multi-chamber system comprises a ring chamber 5, which is arrangedwithin the marginal zone of the base area 2 with formation of aring-shaped outer edge 6 and an inner edge 7. Furthermore, several corechambers 8 are present, said core chambers being defined by bridges andbeing located within the inner edge 7.

The base area 2 of the pneumatic spring piston has a through- andstraight-extending main bridge 9, which is connected with the centerzone of the base area, but which does not extend through the center axis“S” of the piston. No central support body is provided within the directzone of the center axis “S” of the piston.

Furthermore, the base area 2 of the pneumatic spring piston has the twofastening bridges 10 with an area size adequate for receiving the firstfastening system 11. The two fastening bridge connect in thisconjunction the outer edge 6 and the inner edge 7 of the ring chamber 5,specifically with inclusion of the main bridge 9, forming in this mannerthe four ring segments A, B, C and D.

The main bridge 9 in turn is connected with a system of four bridgesextending perpendicular to the main bridge, with formation of the twoouter bridges 12 and the two inner bridges 13. Said bridges are arrangedin this conjunction with about the same spacing between each other andexclusively extend from the inner wall 7 to the inner wall of the ringchamber 5. The two outer bridges 12 as well as the main bridge 9 eachchange in this conjunction with a wide surface area into the fasteningbridge 10. Furthermore, the two inner bridges 13 are connected by atransverse bridge 14, which extends parallel with the main bridge 10,clamping the center axis “S” of the piston.

The pneumatic spring piston 1 is constructed in such a way that onesingle mirror plane “X” is present perpendicular to the base area 2,specifically as opposed to the designs known until now.

The pneumatic spring piston 1′ according to FIG. 2 is different from thepneumatic spring piston 1 according to FIG. 1 in that the core chambers8′ are designed in another way.

A total of four bridges, specifically the two outer bridges 15 and thetwo inner bridges 16 extend within the inner edge 7′ of the ring chamber5′ inclined in relation to the main bridge 9′, specifically withformation of a fan-shaped structure. Said four bridges extending in theform of a fan merge in this conjunction in the area of the inner edge 7′of the ring chamber 5′ in the form of a common meeting point, whereby ahead chamber 17 is present within said meeting point. Said head chamberis outwardly defined by the inner edge 7′ of the ring chamber 5′. Saidhead chamber is located about half way between the two fastening bridges10′.

Furthermore, the bridges extending in the form of a fan are connectedwith each other by a bridge 18 extending in a curved manner. Said bridgeextends in this conjunction from the fastening bridge 10′ to thefastening bridge. Within the area of the two outer bridges 15, thecurved bridge 18 furthermore extends through the main bridge 9′, withformation of a total of two areas of intersection.

Said pneumatic spring piston 1′, too, is constructed in such a way thatone single mirror plane “X” is present perpendicular to the base area2″. Furthermore, in the present case, too, no central support body ispresent within the immediate range of the center axis “S” of the piston.

FIG. 3 shows a pneumatic spring piston 1″ made of plastic, in particularfrom glass fiber-reinforced plastic, which rests with direct contact onthe spring support 19, which is referred to also as a rocking arm (orrocker). An eccentric support surface 20 is formed in this conjunctionwith respect to the center axis “S” of the piston, said support surfacebeing part of the base area 2″. Said support surface is at the same timethe fastening surface because the first fastening system 11″ is locatedwithin said area. Said first fastening system is connected in a fixedmanner with a second fastening system (e.g. a screw) via a drilled hole21 located in the spring arm 19.

The main bridge 9 (FIG. 1 or 9′ (FIG. 2) extends in particular parallelwith the longitudinal outer edge 22 of the spring support 19,specifically in a way such that the main bridge is located within thesupport area 20 of the pneumatic spring piston 1″, whereby the edges ofthe main bridge and the spring support are substantially aligned witheach other.

The depth of the core chambers 8″ amounts to at least ⅔ of the overallheight “H” of the pneumatic spring piston 1″.

FIGS. 4 and 5 again show details of the first fastening system 11″according to FIG. 3 viewed from two different aspects.

In the present case, the first fastening system 11″ is a metal insert,which in turn consists of a threaded part 23 and a reinforcing rib 24.Furthermore, the reinforcing rib has a number of horizontally extendingbores 25.

The fastening system 11″ is particularly suited for a pneumatic springpiston made of plastic, whereby the plastic extends through the bores 25in a material-locked matter. It is possible also to provide for holdingribs instead of using such bores.

The fastening system 11″ offers the advantage that the stress within theenvironment of the threaded part 23 is reduced. Furthermore, thereinforcing rib 24 provides for a reduction in the deformation of thepiston, which is important when a plastic material us used. This assuresa long useful life of the pneumatic spring system.

If necessary, it is possible also to employ as the first fasteningsystem simple threaded bores or threaded bushes for receiving the secondfastening system, especially when a pneumatic spring piston made ofmetallic materials is used.

What is claimed is:
 1. A pneumatic spring system including a pneumaticspring cover, a pneumatic spring bellows made from elastomer material,and at least one fastener for coupling the pneumatic spring bellows tothe pneumatic spring cover, the system also comprising the followingstructural components: a) a pneumatic spring piston comprising: i) aface area arranged opposite the pneumatic spring cover; ii) a lateralroll off surface; wherein the pneumatic spring bellows connects saidpneumatic spring piston to the pneumatic cover via the at least onefastener; b) a base area having a multi-chamber system that projectsinto an interior of said pneumatic spring piston, wherein saidmulti-chamber system comprises a ring chamber extending within an edgezone of said base area, said ring chamber having a ring shaped outeredge and an inner edge, said outer edge defining at least one corechamber; c) a fastening system disposed within said base area of saidpneumatic spring piston; d) a longitudinal guide rod forming a springsupport; e) at least one additional fastening system disposed within abase area of said pneumatic spring piston, wherein said fastening systemand said additional fastening system are used to anchor saidlongitudinal guide rod to said base area of said pneumatic springpiston; wherein said multi chamber system of said base area has only onemirror plane that is present and perpendicular to said base area of saidpneumatic spring piston wherein said base area has an eccentric supportsurface with direct contact with said spring support.
 2. The pneumaticspring system as in claim 1, wherein said pneumatic spring pistonconsists of glass fiber reinforced plastic.
 3. The pneumatic springsystem as in claim 1, wherein said mirror plane is perpendicular to saidbase area of said pneumatic spring piston.
 4. The pneumatic springsystem as in claim 1, wherein said pneumatic spring piston does not havea central support body within an immediate range of a central axis ofsaid piston.
 5. The pneumatic spring system as in claim 1, wherein saidbase area of said pneumatic spring piston has a main bridge, whereinsaid main bridge is connected through a center axis of said piston. 6.The pneumatic spring system as in claim 5, wherein said main bridgeextends parallel with a longitudinal outer edge of said spring support,and wherein said main bridge is located within a support area of saidpneumatic spring piston, said pneumatic spring piston having asubstantially aligned arrangement of said main bridge and said springsupport.
 7. The pneumatic spring system as in claim 1, furthercomprising at least one fastening bridge having a sufficient surfacearea for receiving said fastening system.
 8. The pneumatic spring systemas in claim 7, wherein said fastening system connects said outer edgeand said inner edge of said ring chamber.
 9. The pneumatic spring systemas in claim 8, wherein said fastening system is disposed in said basearea adjacent to said ring chamber.
 10. The pneumatic spring system asin claim 1, wherein said at least one core chamber has at least onebridge.
 11. The pneumatic spring system as in claim 5, wherein said basearea has at least one additional bridge that extends substantiallyperpendicular to said main bridge.
 12. The pneumatic spring system as inclaim 5, further comprising at least four bridges extendingperpendicular to said main bridge with each bridge being spaced apartfrom an adjacent bridge by a substantially equal margin.
 13. Thepneumatic spring system as in claim 12, wherein said at least fourbridges are spaced apart from each other to form at least two outerbridges and at least two inner bridges and wherein said spring systemfurther comprises at least one transverse bridge extending parallel withsaid main bridge and connecting said at least two inner bridges, saidmain bridge and said at least one transverse bridge forming a chamberenclosing a center axis of said piston.
 14. The pneumatic spring systemas in claim 13, wherein said at least two outer bridges merge into afastening bridge.
 15. The pneumatic spring system as in claim 5, furthercomprising a plurality of bridges extending in a fan shaped pattern. 16.The pneumatic spring system as in claim 15, wherein said plurality ofbridges comprise four bridges in a form of two outer bridges and twoinner bridges.
 17. The pneumatic spring system as in claim 15, whereinsaid plurality of bridges merge into each other adjacent to said inneredge to form a common meeting point.
 18. The pneumatic spring system asin claim 11, further comprising a head chamber disposed within saidcommon meeting point, said head chamber being outwardly defined by aninner edge of said ring chamber.
 19. The pneumatic spring system as inclaim 17, wherein said common meeting point is disposed approximatelyhalfway between said two fastening bridges.
 20. The pneumatic springsystem as in claim 15, wherein said plurality of bridges extending in afan shaped pattern are coupled to each other by a curved bridge.
 21. Thepneumatic spring system as in claim 20, wherein said curved bridgeextends from a fastening bridge through said main bridge within a zoneof said two outer bridges.
 22. The pneumatic spring system as in claim21, wherein said curved bridge has an intersection area disposed withina zone where said main bridge and said outer bridge meet.
 23. Thepneumatic spring system as in claim 22, wherein said fastening systemcomprises at least one simple threaded bore for receiving said at leastone additional fastening system.
 24. The pneumatic spring system as inclaim 1, wherein said fastening system comprises at least two threadedbushes for receiving said at least one additional fastening system. 25.The pneumatic spring system as in claim 24, wherein said at least twothreaded bushes are elastic and rounded off.
 26. The pneumatic springsystem as in claim 22, wherein said pneumatic spring is made fromplastic and said fastening system has at least one metal insert forreceiving said at least one additional fastening system, wherein saidmetal insert comprises a threaded component and a reinforcing rib. 27.The pneumatic spring system as in claim 26, wherein said multi-chambersystem has a depth that is at least ⅔ of an overall height of saidpneumatic spring piston.